3.3. Base URL from the Retrieval URL

3.3. Base URL from the Retrieval URL

If no base URL is embedded and the document is not encapsulated
within some other entity (e.g., the top level of a composite entity),
then, if a URL was used to retrieve the base document, that URL shall
be considered the base URL. Note that if the retrieval was the
result of a redirected request, the last URL used (i.e., that which
resulted in the actual retrieval of the document) is the base URL.